Highly active FeNbO4/NiFeOOH heterojunction induced by coordination activation for efficient and stable industrial water oxidation

Abstract

NiFe-oxyhydroxide (NiFeOOH) derived from in situ reconstruction is considered a genuinely active species in the alkaline oxygen evolution reaction (OER). However, the robustness of its durability remains a subject of debate and challenge. In this work, a pre-catalyst FeNbO₄/NiFeC₂O₄, incorporating high valence metals, was first prepared through hydrothermal-low temperature calcination with oxalic acid as a ligand, and then reconstructed into FeNbO₄/NiFeOOH under oxidative conditions. Performance tests revealed that FeNbO₄/NiFeOOH required only 281 mV to achieve a current density of 500 mA cm⁻², while demonstrating exceptional durability. Notably, when assembled into an anion exchange membrane (AEM) electrolytic cell, an ultrahigh current density of 1 A cm⁻² was achieved at 1.88 V. Physical characterization showed that the coordination activation of oxalate not only induced the formation of the corrosion-resistant FeNbO₄ phase, which enhances stability via partial pressure, but also triggered reconstruction through its oxidative dissolution. Density functional theory (DFT) calculations revealed that the reconstructed FeNbO₄/NiFeOOH heterogeneous interface significantly improves the adsorption of oxygenated intermediates, resulting in a reduced energy barrier for the rate-determining step (RDS).